Issue 77

R. Keshavamurthy et alii, Fracture and Structural Integrity, 77 (2026) 217-229; DOI: 10.3221/IGF-ESIS.77.13

composites enhanced by short carbon fibers at 3 wt% and 6 wt%. For comparison, unreinforced PLA specimens were also fabricated under identical processing conditions. All the samples were tested for flexural strength using a three-point bend test, following the ASTM standards for polymer composites. The results showed a clear improvement in strength as the reinforcement content increased. The PLA composite with the 3% short carbon fiber reinforcement showed a noticeable increase in load-bearing ability, while the 6% reinforced composite had an impressive 88% higher flexural strength than the plain PLA. To examine how the materials failed, SEM has been utilized to assess the samples' fractured surfaces. K EYWORDS . Fused Deposition Modelling, Short Carbon Fiber, PLA Composites, Flexural Strength, Fracture Mechanisms.

Copyright: © 2026 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

I NTRODUCTION

A

dditive manufacturing has reshaped the way engineers think about fabrication and honestly it has done so rather quietly [1]. The ability to build intricate geometries while generating comparatively little waste is not something conventional subtractive processes can easily replicate. Among the many techniques that fall under this broad umbrella FDM stands out as the most accessible and economically practical option for producing thermoplastic parts where dimensional accuracy genuinely matters [2]. Industries ranging from food processing to fashion and general manufacturing have adopted this method to construct components that would otherwise demand considerably more effort and expense [3]. As the demand for structurally capable printed parts has grown researchers have turned their attention toward composite filaments and fiber reinforcements in particular with carbon fibers [4] and glass fibers [5] receiving substantial investigative attention over the past decade or so. Fiber reinforcement is not a new idea. Engineers have been blending fibers into polymer matrices for decades and the mechanical gains are well documented across the literature. Carbon fibers bring an impressive combination of stiffness and low mass and this has made them essentially indispensable in sectors where performance cannot be compromised [6]. Glass fibers are cheaper and still deliver reasonable mechanical performance alongside useful electrical insulation properties though they cannot match carbon fibers in terms of stiffness. Natural fibers sit at the other end of the spectrum offering environmental advantages and moderate strength gains and they degrade over time which is sometimes exactly what a designer wants [5]. Still when the application demands genuine structural performance carbon fiber is generally the reinforcement that gets selected and that preference is well justified [6]. PLA is in many respects the default material for FDM and its widespread use owes a great deal to how easy it is to process as well as its biodegradable character and its relatively low cost. The problem is that neat PLA is not particularly stiff or strong and its thermal resistance leaves something to be desired which limits where it can realistically be deployed [7]. Short carbon fibers change this picture meaningfully by acting on the material at the microstructural level and the improvements in rigidity hardness and thermal stability that result are well supported in the published literature. The processability of PLA is not meaningfully disrupted by the addition of fibers which is practically important when considering FDM as the fabrication route. Sanei and Popescu [8] produced what is arguably one of the more thorough reviews of 3D printed carbon fiber composites examining how parameters such as nozzle temperature bed temperature infill density infill pattern layer thickness nozzle speed and build orientation each contribute to the final mechanical outcome. Both chopped and continuous fiber configurations were covered and the review conveys a reasonably complete picture of where the field currently stands and where its difficulties lie. Dickson et al. [9] showed that integrating fibers into polymer matrices through Fused Filament Fabrication yields substantial improvements in mechanical performance and the work spans both continuous and short fiber composites across several application contexts. Pervaiz et al. [10] took a somewhat broader view and their assessment covers the processing difficulties inherent to fiber reinforced polymer systems alongside a measured discussion of future possibilities for carbon fiber and high performance polymer blends. Yang et al. [11] focused specifically on continuous fiber thermoplastic composites made via FDM and their analysis of how fiber content printing temperature layer geometry print velocity and layer thickness influence mechanical properties is fairly detailed. Marabello et al. [12] examined the mechanics

218